The influence of the human form on visual judgements of movement

Lead Research Organisation: University of Lincoln
Department Name: School of Psychology

Abstract

Humans live in complex societies encompassing millions of people, so social interactions dominate much of human behaviour. These interactions depend on an ability to perceive the moods, intentions and actions of other people, and visual perception is especially important in terms of the richness of the information it can provide. Research has shown that 'actions speak louder than words'; perception of movement plays a fundamental role in many social interactions. This project investigates how human visual motion perception is optimised for perceiving the actions of other people.
Psychologists and cognitive neuroscientists argue that the brain is divided into a set of anatomically distinct processing areas or modules. In the case of motion perception, primitive sensory qualities such as local direction and speed are thought to be processed in one part of the brain (mostly in the occipital lobe), and more complex social attributes such as posture, gait and dynamic facial expression are thought to be processed in another part (the temporal lobe). It is still not clear how the 'sensory' and 'social' processing modules interact. How are social attributes derived from sensory data? Do social attributes actually influence sensory processing? Answers to these general questions should have a major impact on our view of the brain as an organ which specialises in processing social interactions. The proposed research will address them by focusing on three specific issues.
1. It has long been known that inspection of a simple moving pattern, such as stripes drifting in a particular direction, affects our ability to perceive movement in other patterns for a short while afterwards. Subsequently viewed stationary patterns are liable to appear as if in motion for a short while. This kind of adaptation is conventionally attributed to changes in sensory processing, but a recent study claims that sensory adaptation can also be mediated by socially meaningful information in the form of human body postures. Such an effect would indicate a new and highly significant form of interaction between the social and sensory processing modules. A series of experiments will investigate the extent to which static visual information conveyed by human body posture can modulate basic sensory processing of movement.
2. The pace of other people's body movements and expressions during social interactions is crucial because it can indicate affective state, hostility and dishonesty. For example, a fast walking speed can indicate a high level of anxiety or aggression, while a slow walking speed can indicate the opposite. Very little is known about how the pace of natural human actions is estimated on the basis of visual information. It cannot be estimated in any straightforward way from the speed of movement in the images our eyes receive, because image motion varies dramatically with viewing distance. A series of experiments will investigate this issue by studying how visual estimates of the natural speed of body movements are affected by previous exposure to speeded-up or slowed-down human actions. These experiments will employ a novel perceptual effect.
3. Social processing of visual information culminates in a perceptual decision. For example: Is that person walking quickly or slowly? Are they walking towards me or not? All perceptual decision-making must, by definition, involve two components; perceptual information, and a decision criterion according to which the information is classified as consistent with one response ("fast") or another ("slow"). Experiments on perception mostly fail to distinguish between these two contributions to perceptual decisions, but both may make a legitimate contribution to our understanding of how visual information mediates social interactions. The proposed research will employ experimental techniques to investigate the contributions of perceptual and decisional factors to the results.

Planned Impact

ACADEMIC IMPACT

The project will have a range of academic impacts:

Results will enhance the knowledge economy by making advances in our understanding of the fundamental brain processes which underpin human social interactions. The findings will be of interest to researchers in several disciplines including social science, vision science and decision science.

A major output of the project will be a library of videos depicting human actions with precisely defined timing properties. These videos will be made available to fellow researchers via a project web site, to promote further research and advances in our understanding of the perception of human actions.

New experimental techniques developed in the project aim to assess the contributions of perceptual bias and decision bias to visual judgements. These techniques and their results will promote further research on the origin of biases in the growing field of decision science, which aims to study the factors which influence human judgements and choices.

The post-doctoral assistant funded by the project will receive experience and training in novel techniques to study the perception of human actions, as well as mentoring from the PI in terms of early-researcher career development. A crucial element of career development provided by the project will be mentoring in research techniques, management, publishing and conference presentation.

ECONOMIC AND SOCIETAL IMPACT

Broader impacts of the work include the following:

New insights into the origins of social interactions, specifically relating to the hidden brain processes which allow us to judge the pace of human actions, will enrich our understanding of human behaviour and culture.

The project will generate new knowledge concerning how people adjust to changes in the dynamic visual environment by re-calibrating their perception of moving humans, vehicles and other objects in natural scenes.

Anecdotally, it seems to take some time to adjust to the pace of action when one moves to a different natural environment, such as a crowded city street full of people walking quickly, a sports event, or roads and motorways full of fast-moving vehicles. There are also subtle changes in the regular pace of actions during social exchanges in different cultures, to which one must adjust when interacting with members of those cultures (for example, the dynamic properties of gestures and expressions have been found to differ between Mediterranean and Scandinavian cultures).

The results of the project will advance our understanding beyond anecdotal accounts, and provide new insights into the brain mechanisms that mediate this 'adjustment'. The work will promote further research into the differences between environments and cultural groups, and how those differences impact on perception and decision-making. Results may also have implications for procedures designed to take account of such differences, in terms of raising awareness of cultural differences, and potential spin-off benefits for safety issues in speed judgements.
 
Description The project investigated how human observers make visual judgements of the movements of other humans. Results showed that:
- Our perception of human movement is influenced both by incoming sensory data and by decisional biases.
- Judgements of the speed of human actions rely on a combination of simple, low-level and more complex high-level processes in the brain.
- Multiple processing routes in the brain are responsible for our ability to perceive the movement of human figures.
Exploitation Route Important insights into the ways people judge the visual movements of other people. Potential applications in judging mental state and intent from human movement speed (e.g. in sports, slow-motion playback may alter perception of intent by the actor).
Sectors Creative Economy,Digital/Communication/Information Technologies (including Software),Leisure Activities, including Sports, Recreation and Tourism,Culture, Heritage, Museums and Collections

URL http://gmresearch2016.blogs.lincoln.ac.uk
 
Description Potential use of the findings is in progress, as described in a separation section. The organisation which supplies referees for professional football in the UK (PGMOL) is interested in using my findings to ensure that refereeing decisions reviewed by viewing slow-motion playback of incidents in matches are are sound as possible.
First Year Of Impact 2017
Sector Leisure Activities, including Sports, Recreation and Tourism
Impact Types Economic

 
Title Video-based stimuli 
Description Videos of human locomotion were recorded using a high-frame rate camera, which can be used for research on the perception of human locomotion (judgements of speed, intent, and so on). The videos available in the form of 40,000 still-frames. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2016 
Provided To Others? Yes  
Impact Impacts to date have come only from publications produced by the project. The materials are available for colleagues to use in future research. 
URL http://gmresearch2016.blogs.lincoln.ac.uk
 
Title Data from Mather & Sharman (2015) 
Description Participant data relating to published output: Mather, G., Sharman, R.J. (2015) Decision-level adaptation in motion perception. Royal Society Open Science. 2 (12), 150418. 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact None of which I am aware at present. 
URL http://datadryad.org/handle/10255/dryad.101813
 
Title Data from Mather et al. (2016) 
Description Data from: Mather, G., Battaglini, L., Campana, G. (2016) TMS reveals flexible use of form and motion cues in biological motion perception. Neuropsychologia, 83, 193-197. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact None as yet to the best of my knowledge. There was a delay in depositing the data because I had initially also tried to deposit the stimulus materials as well (video frames of human locomotion). After a review the repository was not prepared to accept the video materials because they contained identifiable faces (unknown members of the public), even though the recordings were made in a public location where there was no reasonable expectation of privacy. I have made the videos available on request to individual colleagues rather than via a electronic repository. 
URL http://datadryad.org
 
Description Use of TMS to study biological motion processing 
Organisation University of Padova
Department Department of General Psychology
Country Italy 
Sector Academic/University 
PI Contribution GM devised and set up an experimental study of the brain mechanisms underpinning perception of human locomotion in point-light walker displays. The experiment was conducted at the University of Padua, Italy.
Collaborator Contribution Gianluca Campana and Luca Battaglini contributed to the design, and provided equipment, expertise and technical skills in the use of transcranial magnetic stimulation (TMS).
Impact Conference presentation: Mather, G., Battaglini, L., Campana, G. (2015) TMS reveals dual processing routes for biological motion processing. Perception, 45 (6), 689. Journal article: Mather, G., Battaglini, L., Campana, G. (2016) TMS reveals flexible use of form and motion cues in biological motion perception. Neuropsychologia, 83, 193-197.
Start Year 2013
 
Description Invited international scientific meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A scientific meeting entitled "Perceptual technologies: from laboratory to real life", June 1, 2017, Milan, Italy, organised by Experimental Psychology Unit, Faculty of Psychology, Vita-Salute San Raffaele University, Milano
.
I will present a summary of the work during the project to international colleagues and students, in order to explore scientific and clinical applications of the work.
Year(s) Of Engagement Activity 2017